Role of segregation in InAs/GaAs quantum dot structures capped with a GaAsSb strain-reduction layer

Abstract

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Kinetic Monte Carlo simulations and cross-sectional scanning tunneling microscopy as tools to investigate the heteroepitaxial capping of self-assembled quantum dots

“…34 . Along these same lines Haxha et al 35 reported that intermixing of 3 atomic layers was needed to achieve good agreement with experimental results. This is not in contradiction with the results we present below since the model presented by Haxha et al is a mean field model and in order to describe the intermixing captured by our KMC model it was necessary to explicitly include exchange between surface and subsurface atoms.…”

Capping of InAs/GaAs Quantum Dots for GaAs Based Lasers

“…The most common capping materials used for the reduction of strain inside dots are InGaAs (Dasika et al, 2009;Kim et al, 2003) and GaAsSb (Haxha et al, 2009;Bozkhurt et al, 2011;Ulloa et al, 2007;Akahane et al, 2004), sometimes InAlAs or some combination of these materials is used (Liu et al, 2005;Kong et al,2008). Strain reducing layers covering InAs dots are used to shift the emission wavelength to 1.3 µm and 1.55 µm, typical of optical fibre communication.…”

“…To be embedded in a functional structure, dots must be covered by a capping layer. Capping of quantum dots is currently a very important topic of research (Bozkhurt et al, 2011;Dasika et al, 2009;Haxha et al, 2009;Kong et al, 2008). The overgrowth process is essential to obtain dot parameters necessary for the realization of novel optoelectronic devices.…”

Effect of annealing in the Sb and In distribution of type II GaAsSb-capped InAs quantum dots

“…Furthermore, the difficulty of incorporating Sb on GaAs has been repeatedly reported in the literature [15]. Indeed, the effect of interdiffusion, which affects the relative composition of In/Ga and As/Sb in and around the QDs, is still debated [16,17]. An alternative approach to control the Sb distribution is the use of postgrowth thermal annealing that can be used to tailor the band alignment, the wave function overlaps, and hence the recombination dynamics in the InAs/GaAsSb type II QDs [18].…”